the boston marathon. president obama and the first lady michelle obama will be here as well. we will have special coverage, anderson cooper and i will begin that coverage at 9:30 a.m. tomorrow morning. until then thanks very much for watching, our nonstop special coverage of the aftermath of the boston bombings continues now. >> out front next, we begin with breaking news, significant development in the investigation here in boston, according to sources, policeng for someone they saw on video as a possible suspect. plus what we're just learning about the devices used during the bombings and how authorities are using that information they were trying to piece together to locate the attacker. and the poison ricin sent to our lawmakers and this time to the president of the united states. let's go out front.

good evening, everyone, i'm erin burnett in boston and we begin out front tonight with breaking news, a possible suspect in the boston bombings. here's what we know at this moment. according to sources who talked to cnn, authorities have a poss based upon analysis of video of a department store, lord & taylor department stores right near the second blast. federal investigators have made in their words significant progress in the case. the possible suspect is being described as a male who was wearing a white baseball cap backwards, a light colored hoodie and a black jacket. we're awaiting an fbi press conference within the hour and we're going to bring that to you live as it happens. i want to bring in our national

correspondent john king. what is the latest that you know on this possible suspect? >> the latest ishat video authorities to believe thatough video analysis was from a department store, lord & taylor. show what is they believe to be the drop, the placement of the second explosive device. now my understanding is that the images of that have been distributed to law enforcement officials, there was some confusion earlier in the day and now we're getting it from the fbi, from here in boston, from the justice department in washington from the boston police and the governor of massachusetts told cnn a short while ago, there are no arrests, no one in custody. i will say i spoke to the boston mayor and he said that when he was briefed this morning he

became quite optimistic a big break through was imminent. >> the government on monday afternoon along the investigation that's going on, i was briefed early this morning about the investigation and i think we're making head way. i hope that in the near future we have a definitive answer to this question of who did it. but until the fbi is satisfied they have the right person, we can't go public on it at all. >> yeah, the mayor also confirmed source accounts that it was lord & taylor was the department store where they got the test video. i was also told by a source that there was a video by a boston television station that was around that spot at the same time and they know they have been going through this definitely much more optimistic today, and they have what they think is the placement of the second device, they're going

back and looking at the first location as well, trying to sort things out. but this public briefing by the fbi and other authorities, was supposed to be at 1:00, moved to 5:00, and now at 7:00. that courthouse was evacuated because of a bomb threat but also why we got zero public information from the authorities. >> viewers are wondering and they're speculating and asking questions as are we. but what is the whole question today of in custody arrested, what does that mean? do they really know where this person is, and as you have emphasized, the video that they have from the lord & taylor is the placement of the second device so. there's still a question about whether it was one person or multiple people and who would have dropped the first one. >> we're trying to get the possibility of a second suspect, but we do know gh this first one here, i was told by several authorities they have a very

good facial of the enhancement of the video at the lord & taylor site. we have both from a federal official, a boston official saying that an arrest had been made or at least an effort to make an arrest was under way. several other reporters reported the same thing. there's no question now that officials were out ahead of themselves. but we're now told that no arrests have been made. he said based on his knowledge, no arrest, no one in custody and no one being questioned. obviously you can bring someone in to question them and they are not arrested. but the governor says that base it upon his best information there was nobody talking to law enforcement in any capacity. >> they want to have some definiti definitive. but i want to

fbi profiler, mike sullivan and former acting director of the atf in the conversation here with john and myself. mike, let me ask you what do you make of what john's reporting on here, that their possible second suspect. when you put all that together, what do you take away? >> okay, i can't hear me. let me go to you, john douglas, former fbi profiler. when you listened to what john was saying, right now there's a fast and furious scramble tonight whether to find this person or arrest this person, perhaps another suspect. who do you think this person is? >> well, that's a really the most difficult part in this type of case, it's not like a case

such as the yuuna bomber profil in the early 8 0s. what you're trying to determine is the motive. it's not like going to a homicide and you're trying to do victimology on a specific victim, you analyze the specific evidence, the autopsy report. here the victims are so random you really then have to shift to the forensics. when i work a bombing case, i would go to our lab, tell me the degree of sophistication, or the lack of sophistication of this bomb s it even dangerous for this person that's making this device or is it something you can pick up off the internet and do it yourself? and then based upon that, things have changed, you really have to rely on the witness of the public. in this case we have no one claiming responsibility, we have not received any communique as far as we know. and again, unfortunately, many times, in our work we have to

wait for multiple cases to try and tie in, if there's other cases that will happen in the future. so it's really, really a difficult case. >> and what does that lead you to believe in terms of people have wondered, that kind of quote unquote lone wolf nature of this type of person. you have to say somebody is this person's wife, this person's sister, this person's daughter, this person's friend, this person's co-worker. has anyone done anything unusual na you know this person. when law enforcement is reaching out in this manner, is it somebody that truly could have been operating alone? >> it's a good technique used by law enforcement, because what you're trying to do is you're -- when you can't put a profile together, you're drying to identify behavior. and generally, offenders like this do not work in a vacuum, there's something, they'll speak about their problems, whatever their issues are, whatever their

motivations are, they also will oftentimes try out the device, they just don't show up and for the first time and use this device. they'll use smaller devices just to see if in fact will work. and kind of go through an exercise, kind of go through a practice. but the police are doing the right thing, but i believe that the solution of the case is going to come from the public. unfortunately, again in law enforcement, we have to wait for the offenders to make a mistake, the mistake that this offender would have made that he wasn't aware of, all the surveillance cameras that were on at that particular time, people with their phones capturing the runnerss they crossed the finish line. so we're going to have to rely on the public. >> john, thank you very much for taking the time. and to our john king for his reporting. and the question mark right now as to whether in will be a press

conference from law enforcement authorities during this hour. still to come, we're going to go through the clues of what actually was in those bombs, analyzing the nails and the bebes in the bombs that could actually lead police to the terrorists. and some strange happening on cyberspaces and0 monitoring th jihad websites and finding something interesting tonight. ♪

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the nails and the bebe that were used in the bomb to try to find out exactly where the parts were purchased and who bought them. as we have shown you there are pictures that show perhaps a serial number that might give you at least the manufacturer if not the point of final sale. our tom foreman is out front. tom, as you have been looking through this, how are investigators trying to look through the origin of the bomb parts which show parts of serial numbers but not in full. it's tantalizing, but not all the information. >> well, one of the keys to the way they're going to track this town, erin, and you mentioned just a minute ago, pictures, we said yesterday that pictures are going to be key to all of this and today they have been very excited about this particular picture which was taken not far from where you're standing today erin. there's a package in front of a railing that has people behind

it. coupled with another video coming from a camera on top of a lord & taylor's across the street. let me jump from around behind that camera and show you the point of view if you were up there looking down. see where that mailbox is? that's where the bombing took place. let's get our model and talk about the payment of everything. you are right over in this area, this has been cnn's position right over here. lord & taylor's is right over here. and our model, it's yellow. and look closely because this camera that we're fog about is actually right up there on the corner of the building and that is the second explosion site right down there. you can see that is a completely clear line of site if in fact they have an image of a bomber, it would be a good one from that angle. then you could see the other side up the fifth street. that was the first explosion, that was the second explosion. buy does all this matter? it matters, erin, because as you

try to get to that physical evidence, it really helps if you have some idea whom you're following, even if it's six or seven different people that are shown in these shots you can start tracing them and find the real origin of these relatively common items that were found in the bomb. >> common items, the pressure cooker and we're looking at one, it is a nestic item. but they're also in addition to going through the surveillance, they're trying to essentially rebuild the bombs. >> the backpack you got the pre cooker, this is one of the items. we talked how one of these explosions, parts of this may have been globe up. and then there are other things like ignition pieces. why do they want to put all this together? because the configuration of all these things put together will tell you whether or not you have all the parts. because the part you're missing

may be the key part that links somebody who was spotted on this street with all of this stuff. if you can link those together, you not only have a better chance of their rowing in on who was here and purchased this stuff and making an arrest, but also having a case that can stand up later on when you have to deal with all of that. >> tom form, thanks very much. was it dope remotely, was it done by way of a timer. if you look at the timeline of the evidence.

where was it sourced from, it can help in terms of building a case. you also want to make the strongest possible case. you also want to see the evidence here that you can identify the suspect as well. and if there's any particular signature of the bomb, there might be signatures of other bombs from other bombmakers. >> we have been showing our picture to our viewers if you see these wires on the ground on these cones, we also see what appears to be melted matter, whether it bebes and nails. but what does the substance of the device tell you. >> in terms of things like the beebes and the nails, that obviously suggests that they're trying to get maximum injury and maximum death as a result. and that's the shrapnel, where they place it also determines that they may get some additional shrapnel as well if they're doing it near a metal mailbox or a can as well. they do that to cause maximum

injury. >> let me just ask you right here. this is obviously where everything was stored and it was one of these, a pressure cooker, a domestic item. does this make it stronger or weaker shrapnel as well. then you have to consolidate something inside here. and then you have to detonate it and that's where you get the wires and the circuit board and where you're going to get a spark. they say it's not military grade in terms of the compound. so that pressure will build up and obviously explode. >> and is your understanding from what you have seen so far, and i know you have been going through the pictures and the video that this would have been a remote detonation. >> i'm going to let the experts make that determination and they will. the expert also do this type of post blast investigation will come to some conclusion as to

whether this was detonated remotely or detonated in some way via a timer. as we told you last night, he was hoping those -- the homeland security chairman committee will be back with us this hour and we're going to see if we have some news and some more information about the bombs themselves. authorities are doing everything they can to try and locate the bomber. with the chatter on jihadist websites reveels about who might be responsible. we have new details for you next. plus immediately after the blasts, emts strung into action. we're going to meet the man who treated all of the three who were killed in the bombing. mine was earned in djibouti, africa, 2004.

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we begin with breaking nice, deborah f deborah farric is with me and she has information on what swrefrts are looking for. >> one photo that was making the rounds pretty early on in the day, that's of particular interest is of who gentlemen who were seen by the finish line, they're talking with one another and they're each carrying bags that were a little bit out of proportion. those are the kinds of things that investigators are looking at. nobody is calling them anything more than witnesses who they would like to speak to. and that's one of the thingser there are other groups of men they're looking at as well.

people who are carrying something that maybe they shouldn't have been carrying thet of the incident. it did reach the higher levels today, people looking at this photo. >> and at this point, they just want to talk to them and find out what they knew, but to make it clear, two men at the finish line that had bags that were really stuffed. >> and the things that were getting from the fbi, for example one was the backpack, one may be a duffel or a rucksack, those descriptions are consistent with one or more of the pictures of people in the crowd that they're looking at. so again, they're really trying to get rid of all that sort of visual debris and focusolks who import who they think may have had something to do with this. but again, you take a big picture, you got to piece it together and you got to isolate those most important elements. >> now you know how many people

were involved and you got to go through each one of them. we have been looking at the question of foreign versus domestic terrorism and the chatter they have been monitoring on jihadist websites. >> i spoke to two different people today to get a take on they're thinking about over there. what's so interesting is that there has been very little chatter, almost no chatter. usually these islamist jihad did forms that light up whenever there's been an attack. they have actually been quiet. nobody has claimed credit for this. nobody related has claimed credit for this. ase have seen for example in other bombings. also what's understand usual according to the person i spoke to overseas. th he said this one is strange, this one feels different. bombings have a pattern, and this one doesn't have a pattern. when you think of all the bombings that have been tried in the united states, the times

square bombing, what's unique about this device is that it actually worked it was able to do what it was supposed to do. others, for example the times square bomber, didn't do it. so there was a level of sophistication to these two devices and that's another thing that actually doesn't fit the pattern of a trance national attac attack. >> the intelligence she's just gotten is that there's some photos law enforcement officials are focused on including one which is two men near the finish line with bags that appear to be stuffed more than they order ani arily would have been. we are going to be joined by the chairman of the house homeland security committee who's going to join us with the very latest on the attack, what he knows, what he knows about the suspect and what he knows about the bomb. and a letter sent to president obama has tested positive for the powerful poison ricin.

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significant progress has been made in the boston bombing. the camera was positioned just across the street from the second location and as you can

see, there was quite a lot of space there, they had a completely clear view as our tom foreman has reported, that camera did as for second exploded device. a light colored hooded sweatshirt and a black jacket. we not know if investigators have been able to identify this man. we are now looking at i i want to bring in drew griffin now. we have been waiting for the fbi press conference and i believe you have some more detail on what's going to happen. >> well, yeah, 1:00, 5:00, then a delay of a couple of hours and then another delay, then a tweet that said 8:00 and now i'm just reading a tweet from boston police department, the fbi has cancelled the 8:00 p.m. briefing tonight, there will be no briefing. so they may be making

significant progress but they're not going to share that officially with us, leading us to rely on our sources, some speculation and just wondering what this actually means in terms of this investigation. but that's about all i can tell you. there are a lot of journalists as you can see behind me have been waiting all day for this to try to get some kind of official statement on any of all the information that's been disseminated through sources, but we're not going to get that tonight now erinknow, i'll have to leave it up to your guests to speculate on what exactly that means. >> that is a question mark, i know, drew, some have said, well does that mean that they're -- they have information that they're not yet ready to share, does it mean they haven't yet tied together strings they want to tie together. but those are the question marks out there. i want to bring in congressman michael paul to get answers. chairman, do you know why this press conference has been delayeded and delayed and

delayed? >> eno, i don't. and as i have been saying for a long time, this surveillance video now we know from lord and taylor, and private videos, it's going to be one of the keys to this case. in addition to the forensics on the bomb it, which is being evaluated at quantico as we speak. and we hope that those results will come out shortly. but as for the delay of the press conference, i don't know. i did come out earlier when there were reports of a suspect in custody confirming that that was not true. >> confirming that was not true. and what is it that your latest understand on that is over the past few days you said the first 48 hours are crucial. but here we are now and have they may significant progress? >> the first 24 hours in a murder case is key, you don't want the trail to get too cold and too scale.

on the other hand, they're going to have the best evidence right now in my judgment are these videos that were taken from security cameras outside lord & taylors, that the fbi is poring through, my guess is they have possible suspects they have seen on this videotape that they're looking at and at some point in time will come back to the public to help their cooperation to track them down. that coupled with the device itself and the forensics, the fbi, what the fbi does at best is its forensics of bombing devices. they're very, very good at tracers, fingerprints, footprints on these devices to find out where it was purchased and who purchased the materials. so from there, they would execute search warrants and hopefully find the terrorists. >> and chairman, let me just interrupt here, we do have some breaking news.

>> there has been an arrest, so you probably aren't aware of in mississippi, there's been an arrest in the ricin case according to two federal law enforcement officials here at cnn. they the arrest was in the tupelo, mississippi area.ell us this? >> yeah, i knew they had a suspect in this case, and i'm glad to see they have been able to apprehend and arrest this individual. and i would again make the assertion that it really has no relation to t boston bombings, it's very reminisce end of the anthrax attacks after 9/11. it's very dangerous when you have people sending poison to federal officers.

the security is very high right now to protect the members of congress. we're very concerned about these packages. after 9/11, we implemented a procedu procedure that changed the way mail gets to the -- >> let me ask you another question about the situation in boston. just in terms of whether the suspects, the people that they talking, looking at right now in some of those photos, can you tell me whether they're confident, whether you're confident from your briefings that that person or those people are still in the area r still nearby, or do they think they could have fled the country or gone far away? >> you know, i honestly can't answer that question. i think that's one of the biggest issues with this case. is that when every stay passes,

you remember the saudi suspect kind of washed out. so the perpetrators are still out there, and every day that passes, the case becomes a little bit colder and more difficult to piece together. but i'll remind your viewers, though, the 93 world trade center center bombing case was masterfully put together by the fbi and the u.s. attorney's office where they pieced together this forensics from the bombing device at the world trade center and were able to attribute that back to the terrorists, that would be ramsey yousef and the blind sheikh at prerp perpetrated that. i do think there's more of a sense of optimism between the fbi and joint terrorism task force in boston that they're getting closer. >> sir, thank you very much, good to talk to you again tonight and we appreciate you taking your time.

and we can confirm that there was an arrest in the ricin that was sent to the president on capitol hill. one preliminary test did test positive today. it went to the president of the united states as well. rescuer workers at the scene of monday's bombing went into overdrive. within 15 minutes of the blast, they had cleared the votes of all critical care victims. they risked their own lives, it's in those moments thaposed t they run to the scene of the destruction. as poppy harlow reports tonight. >> even 32 years as an emt cannot prepare someone for horror like this. >> how hard was monday. >> it was -- the city's worst day in our department's history. >> mike bossy has been saving lives since he was 22 years old.

on monday he was the finish line command in charge of emt response to the terror attack. he saw the worst of it. >> i saw all three fatalities including the 8-year-old. >> you saw martin? >> yes. plus the kids that were hurt. the kids that look like my kids when they were growing up. >> kimberly robert and christopher were right alongside him. >> we were down around -- >> our first patient was a 17-year-old female. she had blast injuries and shrapnel wounds and an arrest material bleed. >> the same age as her son. then they treated a 44-year-old woman. even as reports of more potential bombs coming in. >> she had pieces of the fence

sticking out of her legs and she was burned up a bit and as we were working on her like mike was saying t police tapped her on the shoulder and said you need to go, there's a package behind you, we said we can't go now, we can't leave her behind. >> unwilling to leave no matter the danger. heroism that prevailed above evil. >> i was right there, very close to where the explosion was. there was a whole bunch of patients on the sidewalk and everyone was -- >> i cannot sing the praises higher for any of the ems services, they were there, they tree anned patients, they brought them to several differentospitals across the city. it allowed the hospitals to step up and take care of those patients. >> what was the best that you saw that day. >> i think everyone helping, not just how fast all of our people

came and helped. just the general public, strangers helping other strangers that didn't know them. people that had no training just wanted to help do something. >> i couldn't believe how many people were still there. >> to help. >> yes. everyone just ran in there to help. >> people look for heros, but in boston you just have to look next >> on a day marred by the worst of human kind, we saw the best of humanity. >> poppy, i know when you see it's so humbling to see them. i know they have been trying to get updates on the people they saved, have they been able to do that? >> some have, they see their victim at the worst state and they hope they are able to recover. one of the rescuers said they were able to go to boston

medical center and see their patients one of the patients had improved from critical serious, one wouldn't think that serious is good, but serious is better than critical. and the other thing we talked about was coping, what about the trauma that they have gone through having to treat this, it really was like a war zone, the ied type explosives that exploded. they said they have each other. they can understand. maybe their friends and family can't understand what they're going through, but their fellow emt workers can. you wonder what would i have done. they didn't hesitate. >> they went in and saved the lives. and how amazing that they want to go and meet with t and follow up with those people. >> i said do you still want to keep doing this? are you sure? because none of them have experienced something like this and they said absolutely. >> some of the heroes from this horrific attack, still to come we have more of the breaking

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i'm back here with anderson cooper, he's got a look at what's coming up on ac 2360. >> i will talk to first responders, firefighterers who were at the finish line. who have been there foryears, it's kind of a tradition in their firehouse. they sprang into action and saved lives. they're going to talk about what they saw and how they figured out who to treat first and what this experience has been like for them. >> it's intrutruly incredible. >> there's so many heroes who ra toward the explosions, citizens, first responders, firefighters, police. and so we're trying to highlight as many of them as possible. >> they truly are here hes of. >> we have some breaking news, now we want to share with you on the ricin investigation. we arelearning that an arrest has been made in the two

envelopes where ricin that tested positive. our chief congressional correspondent dana bash is out in front with the investigation. what are you learning, an arrest of a man from mississippi, right? >> that's exactly right. and we now have this from multiple law enforcement officials. i was just texting with one that just confirmed the news here. this man was arrested in tupelo, mississippi and the reason why this is interesting is because that happens to be the hometown or at least the area where senator roger wicker is actually from. now he of course was one of the intended recipients of the letter. the other was president obama which we learned earlier "tod e. we don't have much information about this man except that he was arrested. the thing i can tell you is that late yesterday when senators here in the capitol were briefed, one senator, senator

claire mccaskell came out and told reports, that the initial suspicion was it was a man back in mississippi for lack of a better way to say it, harassing. and it's clear really within 24 hours they went and found him. >> and dan a, i know there were some other scares today, but this man from tupelo, mississippi, hometown of senator wicker's, this is the only person who is responsible for all of the letters, right? >> reporter: they believe so. they believe so. and i'm sorry, erin, literally as you were asking me that question, i looked down at my phone here and got another text from my source who said this was an fbi grab based on united states capital police information. so that's just a little bit more -- a nugget of how this went down. of course, hopefully we'll get more as this unfolds. but they believe that this was the one man who sent the letters. but you're right. there was a lot of drama here on capitol hill, because there was so much anxiety. there is supposed to be no mail

delivered, at least until monday. however, there was somebody walking around this building where i am, the russell building and also the senate hart office building, handing to the front offices some sealed envelopes, which produced a big scare. the hallway down here was locked off. there was partial lockdown in the senate office building for a couple hours. everything was all clear at the end, but it really does go to show you how anxious people here are. particularly since this was the place not long after 9/11 where anthrax was sent and really did disrupt things and people, including myself, were on cipro and other antibiotics because of the scare. now ricin is another issue than anthrax, but still, certainly is an eerie reminder of how you have one big thing in boston and then something else happens and it makes people very much on edge, as you can imagine.

>> it does. and an entire country on edge. thank you very much, dana. with the very latest on that, i'm understanding there was just one person responsible, that person now arrested from the hometown of senator wicker's, tupelo, mississippi, arrested for sending those ricin-laden letters. i want to bring in dr. sanjay gupta, along with retired colonel randall larson, a retired terror expert. obviously, what dana was talking about and capturing it so eloquently was just the fear that this creates. and obviously not linked to this event. this understanding is they weren't certainly talking -- did he choosehis time to do it because of this, who knows. >> right. >> but ricin itself, how hard is it to get ahold of and how dangerous is it? >> three things you want to think about. how hard it is to get ahold of, how easy it is to weaponize and then disseminate. it's caster bean oil. so you can get caster beans for sure. but that second step, erin, to turn into a weapon of some sort is hard. you've got to make it into these

very small particles that potentially could be inhaled into the lungs. so i think in general, turning it into a weapon is a tough thing to do. it's scary, as you point out, anxiety-provoking. and if it did turn into a weapon, it could be very deadly. but i think that that's hopefully not what we're talking about here. >> and colonel larson, talking about the form it could take is significant. the form in the letters was not the most potent form, but still, this person who lives in tupelo, mississippi was able to get it this far along. is that something that concerns you? >> well, from a legal perspective, erin, this is a very serious crime and if convicted, a is he serious punishment. from a national security, perspective, though, mailing home-brewed ricin to someone is not a threat to a large number of people. for instance, a half bound of dry powdered anthrax could kill tens of thousands of people. but an envelope with ricin in it, i would say a .38 caliber weapon is probably a greater

danger. nevertheless, this is going to be a very serious crime, and hopefully we've got the perpetrator in custody. >> and sanjay, on that question, when he talks about ricin versus anthrax, remember those awful anthrax scares that dana was talking about. which is more difficult to obtain? >> it's a good question. i think probably as colonel was saying, the anthrax, that's a bacteria, that makes those spores that reintroduces. ricin is from a plant, and easi easier obtain. it takes leshrax to kill an individual than ricin. they both require small amounts but i think in terms of obtaining t it's probably the anthr anthrax, something that can occur naturally, but difficult to isolate. >> colonel larson, what would be your biggest fear when you think about someone sending something through the mail? >> anthrax is one of the easier ones to make, easier ones to isolate, as sanjay said.

and that's one we're concerned about. that one -- that's not contagious. small pox, which is contagious and deadly, those are the two thankfully, that's the two pathogens we're most prepared to respond to that we have worked on very hard since 9/11 and the am amerthax case. >> but. >> it is a big but, because we don't talk about these things enough, unless something like this happens. and i think if you start talking with people at e cdc who say, look -- and colonel larson for that matter, how prepared are we, how much have we done to be able to protect not only communities but the country as a whole. i think it's tough to say. you talk about small pox, that's always sort of the worst-case scenario. but this will be -- i think serve as a reminder, i think. >> colonel larson, sanjay, thanks to both of you. we're glad to report there is an arrest in that awful case tonight. we'll be right back. ♪

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all right. our two breaking headlines of the hour. there has been an arrest in the letters that were laden with ricin sent to a u.s. senator and the u.s. president. a man who lives in tupelo, mississippi, the hometown of senator wicker, the first recipient of one of those letters. so we have an arrest there. and the other news that we have, investigators focusing in very closely on one specific photo that has two men with bags that

seemed to be more full than they should be near the finish line. theye lot of photos. they say they just want to talk to these people. but that is the very latest that we have. they're looking at pictures of congregated groups of men to try to ask those questions. we'll be back here live at 11:00. in the meantime, though, "ac360" starts right now. >> thanks very much. good evening, everyone. as erin said, breaking news tonight on two fronts. late word from two federal law enforcement officials that there is an arrest in connection, as erin said, with the poison letters sent to the u.s. president and the u.s. senator. new developments as well in the bombing case to tell you about. and obviously, it has been a roller coaster day foreople here, emotionally and in terms of the facts of the story, it is not over yet. a short time ago, the fbi, again, postponed a news briefing that was originally pushed back from the 5:00 hour. it was supposed to be then at the top of the 8:00 hour. we don't know why this has been pushed back. we hope to learn more throughout the hour. firsthough, we want to check in with joe johns, on the de